bug#24757: 25.1.50; url-cookie.el creates phantom cookie for HttpOnly

[Alain Schneble]

Processing an HTTP response with a Set-Cookie header and HttpOnly
attribute creates a phantom cookie with name HttpOnly.  url-cookie.el
(url-cookie-handle-set-cookie) handles the additional HttpOnly attribute
as the name of an additional cookie, thus interpreting Set-Cookie header
value as it would contain multiple cookies.  This is wrong.  See also
RFC6265 HTTP State Management Mechanism, section 4.1.2.6:
https://www.rfc-editor.org/rfc/rfc6265.txt.

Here's a recipe to reproduce this issue:

- emacs -Q
- Eval the following fragment:
  (let ((file (make-temp-file "CookieHttpOnly")))
    (with-temp-buffer
      (insert
       "(setq url-cookie-storage nil)\n"
       "(setq url-cookie-secure-storage nil)")
      (write-file file))
    (setq url-cookie-file file)
    (url-retrieve-synchronously "https://en.wikipedia.org/wiki/GNU_Guile";)
    (url-cookie-write-file)
    (find-file file))
- The visited cookies file should now contain two cookie entries:
  ("en.wikipedia.org"
        [url-cookie "WMF-Last-Access" "21-Oct-2016" "Tue, 22 Nov 2016 12:00:00 
GMT" "/" "en.wikipedia.org" t]
        [url-cookie "HttpOnly" nil "Tue, 22 Nov 2016 12:00:00 GMT" "/" 
"en.wikipedia.org" t])
  => The second cookie entry is not expected.

I would be happy to arrange a patch to solve this issue, but would like
first to discuss which approach to choose:

1. Simply ignore any HttpOnly attribute/flag on a Set-Cookie header
   value.

2. Extend the url-cookie cl-defstruct to contain an additional slot
   HTTPONLY.  Its value would be t if HttpOnly attribute was detected in
   Set-Cookie's header value, nil otherwise.

I could live with both.  What would you prefer?

Alain





In GNU Emacs 25.1.50.1 (x86_64-w64-mingw32)
 of 2016-09-27 built on MYNGB
Repository revision: bbf1ffd7c74bdf3ea766580788f7f4adb98a47f0
Windowing system distributor 'Microsoft Corp.', version 10.0.10586
Configured using:
 'configure --prefix /c/usr/bin/emacs-25.1 --without-imagemagick'

Configured features:
XPM JPEG TIFF GIF PNG RSVG SOUND NOTIFY ACL GNUTLS LIBXML2 ZLIB
TOOLKIT_SCROLL_BARS

Important settings:
  value of $LANG: DES
  locale-coding-system: cp1252

Major mode: Emacs-Lisp

Minor modes in effect:
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  icomplete-mode: t
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Recent messages:
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